Transported material transporting device and image processing apparatus

ABSTRACT

A transported material transporting device including: a power transmission switching mechanism configured to switch the transmission of the power between the intermediate gear and the cam drive gear between a transmitted state and a blocked state; a detection lever provided in the reversing path and configured to detect the presence or absence of the material to be transported which enters the reversing path; and a blocked-state locking mechanism configured to lock the blocked state of the power transmission switching mechanism when the discharging roller is in the released state, wherein the locked state of the blocked-state locking mechanism is released and the power transmission switching mechanism is switched from the blocked state to the transmitted state upon detection of the position of the trailing end of the material to be transported entering the reversing path by the detection lever.

BACKGROUND

1. Technical Field

The present invention relates to a transported material transportingdevice configured to reverse a material to be transported, such as aprinted material transported by transporting rollers with a firstsurface faced in one direction, by switching the direction of rotationof the discharging rollers between a normal rotation and a reverserotation and transport the same with a second surface of the material tobe transported faced in the one direction and, more specifically, to thetransported material transporting device which is configured to be ableto switch the state of the discharging rollers between a nipped stateand a released state at optimal timings irrespective of the length ofthe material to be transported, and an image processing apparatus havingthe transported material transporting device.

2. Related Art

As described in JP-A-2007-230657, image scanning devices such as copyingmachines, facsimile machines or scanners having an Auto Document Feederas an example of a transported material transporting device are alreadydeveloped. The image scanning devices as shown above include imagescanning devices which are capable of scanning image data recorded onboth front and rear surfaces of a material to be transported(hereinafter, referred to also as “paper”) continuously. The imagescanning devices described above are configured to guide a paperdelivered with a first surface thereof up into a semi-loop shapedtransport path, in which the transporting roller, an image scanningportion, and the discharging roller are disposed, transport the paperwith the first surface down, and perform image scanning of the firstsurface.

Subsequently, the image scanning device switches the direction oftransport to guide the paper into a reversing path and guides the sameagain into the transport path, thereby transporting the paper with asecond surface, which is an opposite surface from the first surface,faced down, and performs image scanning of the second surface.

Switching of the direction of paper transport and switching of the stateof the discharging roller between the nipped state and the releasedstate, which are required when performing the image scanningcontinuously over the first surface and the second surface of theabove-described paper, are performed by the transported materialtransporting device (hereinafter, referred to also as “papertransporting device” at preset certain timings.

The paper transport path is downsized in accordance with a tendency ofdownsizing of the image scanning devices, so that the length of thetransport path is reduced. Therefore, when transporting a long paper, aportion of a paper delivered to the reversing path and a portion of thepaper discharged out from the transport path pass each other at a nip ofthe discharging rollers during the transport of the second surface.Therefore, the discharging rollers are brought into the released stateat the timing when the portions of the paper pass each other asdescribed above, thereby allowing the both to pass each other.

JP-A-2007-230657 and JP-A-2004-2024 are examples of related art.

However, if the switching of the direction of transport of the paper andthe switching of the state of the discharging rollers between the nippedstate and the released state are performed uniformly at the presetcertain timings, the length of the paper that can be provided for thedouble-sided scanning is limited. If a paper having a length other thanthose supported by the paper transporting device operated at the certaintimings, transport failures such as skewing or jamming of the paper maybe resulted.

It is also possible to perform the switching of the state of thedischarging rollers between the nipped state and the released stateseparately from powers of the transporting roller and the dischargingroller using a separate power, for example, a solenoid or the like whichis disclosed in JP-A-2004-2024. However, it results in increase innumber of components and complicated structure, thereby leading to thecost of the paper transporting device.

SUMMARY

An advantage of some aspect of the invention is that switching of thestate of discharging rollers between a nipped state and a released statecan be performed at preferred timings according to the lengths ofmaterials to be transported irrespective of the difference in length ofthe transporting materials.

According to a first aspect of the invention, there is provided atransported material transporting device including: a transportingroller, a discharging roller, a drive motor, a nip-release switchingmechanism, a planetary gear mechanism, a power transmission switchingmechanism, a detection lever, and a blocked-state locking mechanism. Thetransporting roller is configured to transport a material to betransported on a transport path by rotating in a direction of normalrotation. The discharging roller is configured to discharge the materialto be transported on the transport path by rotating in the direction ofnormal rotation, deliver the material to be transported to thetransporting roller via a reversing path by rotating in a direction ofreverse rotation, and be capable of assuming a nipped state and areleased state. The drive motor serves as a driving source of thetransporting roller and the discharging roller. The nip-releaseswitching mechanism is configured to switch the state of the dischargingroller between the nipped state and the released state by the rotationalposition of a cam drive gear. The planetary gear mechanism includes afirst planetary gear configured to transmit a power to the cam drivegear when the drive motor rotates in one direction, and a secondplanetary gear configured to transmit the rotation in the same directionas the first planetary gear to the cam drive gear via an intermediategear when the drive motor rotates in the other direction. The powertransmission switching mechanism is configured to switch thetransmission of the power between the intermediate gear and the camdrive gear between a transmitted state and a blocked state. Thedetection lever is provided in the reversing path and configured todetect the presence or absence of the material to be transported whichenters the reversing path. The blocked-state locking mechanism isconfigured to lock the blocked state of the power transmission switchingmechanism when the discharging roller is in the released state. Thelocked state of the blocked-state locking mechanism is released and thepower transmission switching mechanism is switched from the blockedstate to the transmitted state upon detection of the position of thetrailing end of the material to be transported entering the reversingpath by the detection lever.

In this configuration, the timing of translation of the dischargingroller from the released state to the nipped state is set to be “upondetection of the position of the trailing end of the material to betransported” which is not affected by the difference in length of thematerial to be transported. Therefore, the switching of the state of thedischarging roller between the nipped state and the released state canbe performed at a preferred timing corresponding to the length of thematerial to be transported irrespective of the difference in length ofthe materials to be transported. Also, the timing of translation is seton the basis of the normal and reverse rotation of the single drivemotor and the movement of the detection lever configured to detect thepassage of the transported material. Therefore, increase in number ofcomponents is prevented. In addition, the simple structure of theapparatus is achieved. Therefore, reduction of the product cost is alsoachieved.

Preferably, the cam drive gear includes on a peripheral surface thereofan entirely toothed portion formed with teeth over the entirecircumference and a partially toothed portion provided partially with atooth missing portion for home position and a tooth missing portion forrelease position, both of which are parts having no tooth providedpartly on the peripheral surface. The first planetary gear engages theentirely toothed portion and the intermediate gear engages the partiallytoothed portion, and the intermediate gear is configured to be capableof being moved by the power transmission switching mechanism between afirst position formed with both the tooth missing portion for homeposition and the tooth missing portion for release position and a secondposition formed only with the tooth missing portion for home position inan axial direction.

In this configuration, the first planetary gear engages the cam drivegear when the drive motor rotates in the reverse direction, for example.Therefore, the rotation of the first planetary gear is alwaystransmitted to the cam drive gear through the entirely toothed portionof the cam drive gear. In contrast, the second planetary gear engagesthe cam drive gear via the intermediate gear when the drive motorrotates in the normal direction. Therefore, the rotation in the samedirection as when the drive motor rotates in the reverse direction istransmitted to the cam drive gear at a portion of the cam drive gearwhere the teeth in the partially toothed portion is formed.

When the intermediate gear is located at the first position, a blockedstate is assumed. The blocked state is the state where the intermediategear and the cam drive gear do not engage at two positions where thetooth missing portion for home position and the tooth missing portionfor release position are formed and no transmission of the power occurs.When the intermediate gear is located at the second position, theblocked state is assumed at a portion where the tooth missing portionfor home position is formed.

Therefore, the rotation and the stop of the cam drive gear can becontrolled by the two tooth missing portions formed on the peripheralsurface of the cam drive gear and the axial movement of the intermediategear, so that the switching of the above-described discharging rollersbetween the nipped state and the released state can be performed at anoptimal timing corresponding to the length of the material to betransported without providing an additional drive unit.

Preferably, the power transmission switching mechanism includes: a camlever, a frictional clutch, and a cam lever drive gear train. The camlever is provided with a solid cam coming into abutment with an endsurface of the intermediate gear and having a cam height in the axialdirection, and is configured to rock about a rocker shaft within a rangeof the rocking angle. The frictional clutch is configured to come intopress contact with the cam lever and transmit a power. The cam leverdrive gear train is configured to transmit the rotation of the drivemotor to the frictional clutch.

In this configuration, the power transmission switching mechanism whichis operated using the rotation of the single drive motor can beconfigured, so that the intermediate gear can be moved in the axialdirection by a predetermined stroke by adjusting the cam height of thesolid cam which acts on an end surface of the intermediate gear byswitching the rocking position of the cam lever. Since the frictionclutch is employed as a member for transmitting the power by actingdirectly on the cam lever, the power transmission to the cam lever isensured, and the quick switching of the rocking position of the camlever is achieved.

Preferably, the cam lever includes a sector gear portion configured totransmit the power by engaging the intermediate gear when moving theintermediate gear from the first position to the second position.

In this configuration, execution of the movement of the intermediategear toward the first position and the second position is ensured by theengagement between the sector gear portion and the cam lever drive geartrain without causing a slippage, so that the reliability of the powertransmission switching operation is enhanced.

Preferably, the blocked-state locking mechanism includes a restrictingmember provided at a working end of the detection lever and an engagingprojection provided on part of a peripheral surface of the cam lever andcoming into abutment with the restricting member, the restricting membercomes into abutment with the engaging projection to restrict the rockingmovement of the cam lever after the material to be transported entersthe reversing path and the detection lever detects the passage of aleading end of the material to be transported until the passage of atrailing end of the material to be transported is detected in a state inwhich the cam lever locates the intermediate gear at the first position.

In this configuration, the blocked-state locking mechanism is achievedwith a simple structure in which only the restricting member and theengaging projection are provided, and smooth switching of the powertransmission switching mechanism between the transmitted state and theblocked state is achieved by associating the movement of the detectionlever which detects the position of the transported material enteringthe reversing path and the timing of the blocked-state locking mechanismbetween the locked state and the unlocked state without providing anadditional position sensor or a drive unit.

A second aspect of the invention is an image processing apparatusincluding: an image processing executing unit; and a transportedmaterial transporting device. The image processing executing unit isprovided in a transport path at a position between a transporting rollerand a discharging roller and configured to execute image processingactions continuously on an opposed surface of a material to betransported which is transported by the transporting roller. Thetransported material transporting device is configured to switch thedirection of transport of the material to be transported to cause thematerial to be transported to enter a reversing path and reverse thesame so that a first surface and a second surface opposite therefrom areopposed to the image processing executing unit after having executed theimage processing on a first surface of the material to be transported.The transported material transporting device is a transported materialtransporting device according to the first aspect of the invention.

In this configuration, the first surface transport and the secondsurface transport which is achieved smoothly without being affected bythe length of the material to be transported owing to the same effectsand advantages as those described above. Therefore, the image processingto be performed on both surfaces of the material to be transported isachieved with a high degree of accuracy without being affected by thelength of the material to be transported.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a perspective view showing an appearance of a papertransporting device according to a first embodiment of the invention.

FIG. 2 is a side cross-sectional view showing an internal structure ofthe paper transporting device according to the first embodiment of theinvention during a first surface transport.

FIG. 3 is a side cross-sectional view showing an internal structure ofthe paper transporting device according to the first embodiment of theinvention when the first surface transport is ended.

FIG. 4 is a side cross-sectional view showing an internal structure ofthe paper transporting device according to the first embodiment of theinvention when a second surface transport is started.

FIG. 5 is a side cross-sectional view showing an internal structure ofthe paper transporting device according to the first embodiment of theinvention during a first half of the second surface transport.

FIG. 6 is a side cross-sectional view showing an internal structure ofthe paper transporting device according to the first embodiment of theinvention during an intermediate part of the second surface transport.

FIG. 7 is a side cross-sectional view showing an internal structure ofthe paper transporting device according to the first embodiment of theinvention during a latter half of the second surface transport.

FIG. 8 is a perspective view of the paper transporting device accordingto the first embodiment of the invention showing a nip-release switchingmechanism and a gear train which is responsible for actions ofrespective portions.

FIG. 9 is a perspective view of the paper transporting device accordingto the first embodiment of the invention showing the nip-releaseswitching mechanism and a gear train provided in the periphery of a camdrive gear in a state in which discharging rollers is in a nipped state.

FIG. 10 is a side view of an operating state of the paper transportingdevice according to the first embodiment of the invention showing astate in which the cam drive gear and a drive motor of the gear train inthe periphery of the cam drive gear rotate in a normal direction.

FIG. 11 is a side view of an operating state of the paper transportingdevice according to the first embodiment of the invention showing astate in which the cam drive gear and the drive motor of the gear trainin the periphery of the cam drive gear rotate in a reverse direction.

FIG. 12 is a side view of an operating state of the paper transportingdevice according to the first embodiment of the invention showing astate in which a cam lever, a detection lever, and the cam drive gear islocked in a power blocked state.

FIG. 13 is a perspective view of the nip-release switching mechanism andthe gear train provided in the periphery of the cam drive gear of thepaper transporting device according to the first embodiment of theinvention showing a state in which the discharging roller is in areleased state and the cam drive gear is locked in the power blockedstate.

FIG. 14 is a side cross-sectional view of the nip-release switchingmechanism and the periphery of discharging rollers of the papertransporting device according to the first embodiment of the inventionshowing a state in which the discharging rollers are in a released statein an enlarged scale.

FIG. 15 is a side view of an operating state of the paper transportingdevice according to the first embodiment of the invention showing astate in which a power transmitting state of the cam lever, thedetection lever, and the cam drive gear is being translated.

FIG. 16 is a perspective view of the nip-release switching mechanism andthe gear train provided in the periphery of the cam drive gear of thepaper transporting device according to the first embodiment of theinvention showing a state in which the power blocked state is unlockedand the discharging rollers start translation from the released state tothe nipped state.

FIG. 17 is a side cross-sectional view of the nip-release switchingmechanism and the periphery of the discharging rollers of the papertransporting device according to the first embodiment of the inventionshowing a state in which the discharging rollers are in the nipped statein an enlarged scale.

FIG. 18 is an operation chart of the second surface transport of thepaper transporting device according to the first embodiment of theinvention.

FIG. 19 is a side cross-sectional view showing an internal structure ofthe paper transporting device according to a second embodiment of theinvention when the first surface transport is ended.

FIG. 20 is a side cross-sectional view of an operating state of a clutchmechanism of the paper transporting device according to the secondembodiment of the invention when the first surface transport is ended.

FIG. 21 is a side cross-sectional view of an internal structure of thepaper transporting device according to the second embodiment of theinvention showing a state immediately after having started the secondsurface transport and detected a leading end of the paper by thedetection lever.

FIG. 22 is a side cross-sectional view of the paper transporting deviceaccording to the second embodiment of the invention showing an operatingstate of the clutch mechanism immediately after having started thesecond surface transport and detected the leading end of the paper bythe detection lever.

FIG. 23 is a side cross-sectional view of an internal structure of thepaper transporting device according to the second embodiment of theinvention showing a state in which the second surface transport isproceeded and the leading end of the paper reaches a position upstreamof the discharging rollers.

FIG. 24 is a side cross-sectional view of the paper transporting deviceaccording to the second embodiment of the invention showing an operatingstate of the clutch mechanism in which the second surface transport isproceeded and the leading end of the paper reaches a position upstreamof the discharging rollers.

FIG. 25 is a side cross-sectional view of an internal structure of thepaper transporting device according to the second embodiment of theinvention showing a state immediately after having further proceeded thesecond surface transport and detected the passage of a trailing end ofthe paper by the detection lever.

FIG. 26 is a side cross-sectional view of the paper transporting deviceaccording to the second embodiment of the invention showing an operatingstate of the clutch mechanism immediately after having further proceededthe second surface transport and detected the passage of the trailingend of the paper by the detection lever.

FIG. 27 is a top view of a cam drive gear, a gear train in the peripheryof the cam drive gear, and the clutch mechanism of the papertransporting device according to the second embodiment of the invention.

FIG. 28 is a perspective view of the paper transporting device accordingto the second embodiment of the invention showing an operating state inwhich the cam drive gear, the gear train in the periphery of the camdrive gear and the drive motor of the clutch mechanism are rotated inthe reverse direction.

FIG. 29 is a perspective view of the paper transporting device accordingto the second embodiment of the invention showing an operating state inwhich the cam drive gear, the gear train in the periphery of the camdrive gear and the drive motor of the clutch mechanism are rotated inthe normal direction.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring now to the drawings, a transported material transportingdevice and an image processing apparatus according to the invention willbe described in detail on the basis of first and second embodimentsshown below. First of all, a scanner 1 is exemplified as an embodimentfor carrying out the image processing apparatus having the transportedmaterial transporting device of the invention mounted thereon, and anoutline of an internal structure of the scanner 1 will be described.

The scanner 1 in the drawing is an image scanning device which iscapable of continuously scanning images printed on both a first surface3 of a material to be transported which corresponds to an originaldocument (hereinafter, referred to also as “paper”) P and a secondsurface 5 which is a surface opposite from the first surface 3.

More specifically, as shown in FIG. 1 to FIG. 7, the scanner 1 is madeup of a transported material transporting device 31 configured toperform a first surface transport which guides the paper P supplied withthe first surface 3 faced up to a semi-loop shaped transport path 19having transporting rollers 7 and discharging rollers 13 disposedtherein to cause the first surface 3 to face down, then perform a secondsurface transport which causes the paper P to enter a reversing path 27by switching the direction of transport and guides the same again to thetransport path 19 to cause the second surface 5 down, and an imageprocessing executing unit 35 provided at an intermediate positionbetween the transporting rollers 7 and the discharging rollers 13 of thetransport path 19 and configured to continuously perform an imageprocessing action with respect to the first surface 3 and the secondsurface 5 of the paper P transported by the transporting rollers 7.

The transport path 19 is made up of a path member in which a firsttransporting unit 21, a turning portion 23 and a second transportingunit 25 are disposed in a semi-loop shape. Then, disposed at positionsupstream of the first transporting unit 21 is a feeding tray 39 having aplacing table 41 for placing the paper P, and a fixed edge guide 43 anda movable edge guide 45 that adjust and set the positions of left andright edges of the paper P which is set on the placing table 41.

Disposed in a section from above a distal end portion of the feedingtray 39 to a transporting portion of the first transporting unit 21 inthe transport path 19 are a pick roller 47 configured to feed a topmostpaper P from a plurality of pieces of the paper P set in piles on thefeeding tray 39 in sequence from the top, and a separating roller 49 anda separating pad 51 configured to separate only the topmost paper P fromthe plurality of pieces of the paper P delivered together and feed thesame toward the transport path 19.

The first transporting unit 21 is a portion which receives the paper Pdelivered from the feeding tray 39 described above first, and the paperP in the first transporting unit 21 is transported with the firstsurface 3 faced up.

The turning portion 23 is a portion to reverse the paper P fed from thefirst transporting unit 21 upside down and delivers the same to thesecond transporting unit 25. The above-described transporting rollers 7including a pair of nip rollers, namely, a transporting drive roller 9and a transporting driven roller 11 are disposed at a positiondownstream of the turning portion 23.

The second transporting unit 25 serves to receive the paper P reversedupside down by the above-described turning portion 23, and transport thesame toward the image processing executing unit 35, and further towardthe above-described discharging rollers 13 including the pair of niprollers, namely a discharge drive roller 15 and a discharge drivenroller 17 which are present at a downstream end of the secondtransporting unit 25. The paper P is delivered in the secondtransporting unit 25 with the first surface 3 faced down during thefirst surface transport, and with the second surface 5 faced down duringthe second surface transport.

The discharging rollers 13 are configured to be switched in state by anip-release switching mechanism 55, described later, between a nippedstate and a released state, and allows a leading end 69 and a trailingend 71 of the paper P to pass each other at a nip of the dischargingroller 13, which is encountered when transporting an long paper P.

The reversing path 27 is a path configured to guide the paper P afterhaving ended the first surface transport again to an upstream portion ofthe turning portion 23 of the transport path 19 and reverse the paper Pupside down for the second surface transport as shown in FIG. 3. Adistal end portion 75 a of a detection lever 75 configured to detect thepresence or absence of the paper P faces the reversing path 27.

The image processing executing unit 35 basically includes a transportedmaterial supporting portion disposed above the paper P to be transportedand configured to hold the paper P from above and support the same in anexpanded state (hereinafter, referred to as “a paper supportingportion”) 79, a glass plate 81 disposed below the transported paper P,and an image scanning portion 83 provided in a housing partitioned bythe glass plate 81 and including a fluorescent lamp and alight-receiving sensor.

First Embodiment See FIG. 1 to FIG. 18

A paper transporting device 31A according to a first embodimentdescribed later can be mounted in the scanner 1. The paper transportingdevice 31A includes a drive motor, not shown, which can be rotated innormal and reverse directions, a roller driving gear train fortransport, not shown, configured to transmit the rotation of the drivemotor to the transporting rollers 7 to rotate the same in a normaldirection CCW in a normal state, a discharge roller drive gear train 87configured to transmit the rotation of the drive motor to thedischarging rollers 13 to rotate the same both in the normal directionCCW and in a reverse direction CW, and the nip-release switchingmechanism 55 configured to switch the state of the discharging rollers13 between the nipped state and the released state according to therotational position of a cam drive gear 57.

Furthermore, the paper transporting device 31A includes a planetary gearmechanism 95 having a first planetary gear 101 configured to transmit apower to the cam drive gear 57 when the drive motor rotates in thereverse direction and a second planetary gear 103 configured to transmita power to the cam drive gear 57 via an intermediate gear 105 when thedrive motor rotates in the normal direction, a power transmissionswitching mechanism 121 configured to switch power transmission betweenthe intermediate gear 105 and the cam drive gear 57 between atransmitted state and a blocked state, the detection lever 75 providedin the reversing path 27 and configured to detect the presence orabsence of the paper P entering the reversing path 27, and ablocked-state locking mechanism 141 configured to lock the blocked stateof the power transmission switching mechanism 121 when the dischargingrollers 13 are in the released state.

The paper transporting device 31A is configured to release the lockedstate of the blocked-state locking mechanism 141 and switch the blockedstate of the power transmission switching mechanism 121 to thetransmitted state upon detection of the position of the trailing end 71of the paper P entering the reversing path 27 by the detection lever 75.

Only one drive motor is provided, and the drive motor is configured tobe capable of transmitting the power thereof to the transporting driveroller 9, the discharge drive roller 15, and the cam drive gear 57, andcausing the nip-release switching mechanism 55, the planetary gearmechanism 95, and the power transmission switching mechanism 121 toperform desired actions by switching the direction of rotation thereofbetween the normal direction CCW and the reverse direction CW atpredetermined timings.

The roller driving gear train for transport is a gear train configuredto transmit the rotation of the drive motor to the transporting driveroller 9. The roller driving gear train for transport is integrated witha mechanism which rotates the transporting drive roller 9 in the normaldirection CCW in the normal state even when the drive motor switches thedirection of rotation either to the normal direction CCW or to thereverse direction CW. Specifically, the planetary gear mechanism 95described later and a mechanism which is basically the same as aconfiguration to rotate the cam drive gear 57 in the fixed direction bycombining the intermediate gear 105 are integrated therein, for example.

The discharge roller drive gear train 87 is a gear train configured totransmit the rotation of the drive motor in the normal direction CCW andthe reverse direction CW to the discharge drive roller 15. Specifically,a first transmission gear 88 having a large-diameter gear portion 88 aand a small-diameter gear portion 88 b integrally therewith is providedat a trailing end of the discharge roller drive gear train 87. Then, adischarge roller drive gear 89 mounted at one end of a discharge rollerdrive shaft 91 engages the small-diameter gear portion 88 b of the firsttransmission gear 88, so that the rotation of the discharge roller drivegear 89 is transmitted to the discharge drive roller 15 via thedischarge roller drive shaft 91 without change.

For example, when discharging the paper P fed to the second transportingunit 25 to the outside, the discharge drive roller 15 is rotated in thenormal direction CCW as shown in FIG. 2 and FIG. 7. When causing thepaper P after having ended the first surface transport and moved to aposition shown in FIG. 3 to enter the reversing path 27 as shown in FIG.4, the discharge drive roller 15 is rotated in the reverse direction CWas shown in the same drawing.

The nip-release switching mechanism 55 integrally includes the cam drivegear 57 configured to receive the transmission of the power via theplanetary gear mechanism 95, described later, and the intermediate gear105, a cam shaft 59 having the cam drive gear 57 mounted at one endthereof and extending horizontally toward a center portion of thetransport path 19 in a width direction B, two cams 61 and 61 provided atthe other end of the cam shaft 59, two cam followers 63 and 63 cominginto abutment individually with the two cams 61 and 61, and the camfollowers 63 and 63. The nip-release switching mechanism 55 alsoincludes a roller holder 18 for the discharge driven roller 17configured to rock about a rocker shaft, not shown, within a certainangular range, and an urging member 65 formed of a compression coilspring which presses an upper surface of the roller holder 18 on theside of a free end of the rocking motion and urging the discharge drivenroller 17 toward the discharge drive roller 15. This is the basicconfiguration of the nip-release switching mechanism 55.

The discharging rollers 13 are held in the released state at a positionshown in FIG. 14, at which a distal end portion 61 a, which is thehighest portion of the cam 61, is in abutment with the cam follower 63.The discharging rollers 13 are brought into the nipped state at aposition shown in FIG. 17, at which a proximal end portion 61 b, whichis the lowest portion of the cam 61 is in abutment with the cam follower63.

The cam drive gear 57 is configured to rotate always in the fixeddirection irrespective of the direction of rotation of the drive motorswitched by the action of the planetary gear mechanism 95 and theintermediate gear 105, described below.

The cam drive gear 57 includes on a peripheral surface thereof anentirely toothed portion 107 formed with teeth over the entirecircumference on the distal end side thereof and a partially toothedportion 109 provided partially with a tooth missing portion 111 for homeposition and a tooth missing portion 113 for release position having notooth on the proximal side thereof.

The tooth missing portion 111 for home position is a tooth missingportion which prevents the power from being transmitted to the cam drivegear 57 when the cam drive gear 57 is at the home position, and isformed over the entire length of the partially toothed portion 109. Incontrast, the tooth missing portion 113 for release position is a toothmissing portion which prevents the power from being transmitted to thecam drive gear 57 when the cam drive gear 57 is at the releasedposition, and is formed partially on the partially toothed portion 109in a range nearer the entirely toothed portion 107.

The planetary gear mechanism 95 basically includes a second transmissiongear 96 integrally having a large-diameter gear portion 96 a and asmall-diameter gear portion 96 b which rotate in engagement with thedischarge roller drive gear 89, a solar gear 97 integrally having alarge-diameter gear portion 97 a and a small-diameter gear portion 97 bwhich engages the small-diameter gear portion 96 b, a rocker arm 99which rocks and rotates about a rotating shaft 98 of the solar gear 97,the first planetary gear 101 axially supported at one end of the rockerarm 99 and the second planetary gear 103 axially supported at the otherend of the rocker arm 99.

The first planetary gear 101 and the second planetary gear 103 areconfigured to engage the small-diameter gear portion 97 b with theintermediary of the small-diameter gear portion 97 b of theabove-described solar gear 97 interposed at the center therebetween.

The first planetary gear 101 has a role to rock the rocker arm 99 in adirection to cause the first planetary gear 101 to engage the cam drivegear 57 when the drive motor rotates in the reverse direction CW andtransmit the power to the cam drive gear 57 to rotate the same in thepredetermined direction.

In contrast, the second planetary gear 103 has a role to rock the rockerarm 99 in the direction opposite from the above-described direction whenthe drive motor rotates in the normal direction CCW and transmit thepower to the cam drive gear 57 via the intermediate gear 105 to rotatesame in the same direction as described above.

At this time, the first planetary gear 101 engages the entirely toothedportion 107 of the cam drive gear 57, and the intermediate gear 105engages the partially toothed portion 109 of the cam drive gear 57.

The intermediate gear 105 is configured to be capable of being moved bythe power transmission switching mechanism 121, described below, betweena first position 115 formed with both the tooth missing portion 111 forhome position and the tooth missing portion 113 for release position anda second position 117 formed only with the tooth missing portion 111 forhome position in an axial direction G.

The power transmission switching mechanism 121 basically includes a camlever 129, a friction clutch 131, and a cam lever drive gear train 137(137A, 137B, and 137C). The cam lever 129 includes a solid cam 123coming into abutment with an end surface 105 a on the proximal side ofthe intermediate gear 105 and having a cam height in the axial directionG, and a long hole 127 for rocking movement formed along a circulartrace having a predetermined radius about a rocker shaft 125 and beingcurved into an arcuate shape fitted on a shaft portion 105 b of theintermediate gear 105. The cam lever 129 has a sectoral plate-shapedfree end of the rocking motion, and is rocked within the range of apredetermined rocking angle which is set by the long hole 127 forrocking movement. The friction clutch 131 includes a friction gear 133configured to come into press contact with the cam lever 129 to transmitthe power and an urging member 135 formed of a compression spring, andconfigured to provide an urging force to bring the friction gear 133into press contact with the cam lever 129. The cam lever drive geartrain 137 (137A, 137B, and 137C) transmits the rotation of the drivemotor to the friction gear 133.

The solid cam 123 is provided in the periphery of the long hole 127 forrocking movement, and has a cam surface 123 a inclined smoothly so thatthe cam height becomes the lowest at one end 127 a of the long hole 127for rocking movement and the cam height becomes the highest at the otherend 127 b.

The cam lever 129 includes a friction disk 129 a at the proximal side ofthe rocking movement. The friction disk 129 a is brought into directlypress contact with the friction gear 133 described above, and rocksabout the rocker shaft 125. Provided on apart of the peripheral surfaceof the friction disk 129 a is a sector gear portion 138, which engages athird gear 137C arranged at a trailing end of the cam lever drive geartrain 137 together with the friction gear 133.

The sector gear portion 138 has a role to transmit the power to thethird gear 137C by engaging the same when moving the intermediate gear105 to the second position 117. On other portions of the friction disk129 a which is not provided with the sector gear portion 138, therotation of the third gear 137C is transmitted to the friction gear 133,and then to the cam lever 129 via a frictional force from the frictiongear 133.

The friction clutch 131 includes the friction gear 133 and the urgingmember 135 arranged so as to interpose the friction disk 129 a of thecam lever 129 therebetween as described above, and is formed by placinga flat washer 139, which also serves as a spring seat, on an end surfaceof the compression coil spring, which is the urging member 135, andtightening a tightening screw 136 with a predetermined tightening force.

The cam lever drive gear train 137 includes three gears, namely, thefirst gear 137A, the second gear 137B, and the third gear 137C, and isconfigured as follows. The power is transmitted in sequence from thefirst gear 137A which engages the large-diameter gear portion 96 a ofthe second transmission gear 96 described above to the second gear 137B,and then to the third gear 137C, so that the rotation of the third gear137C is transmitted to the above-described cam lever 129 via thefriction gear 133 or the sector gear portion 138 as described above.

The detection lever 75 is formed of a bent and narrow panel-shapedmember as shown in FIG. 8, FIG. 12 and FIG. 15. The distal end portion75 a of the detection lever 75 is a portion for detecting the presenceor absence of the paper P or the timing of passage of the paper P, andis disposed so as to face the reversing path 27 as described above.

A hook portion 75 b for hooking a spring is provided at a middle sectionof the detection lever 75, and an urging member 76 formed of a tensioncoil spring is provided in a strained manner between the hook portion 75b and a supporting frame 32 on the side surface of the papertransporting device 31A.

A restricting member 143 which is a component of the blocked-statelocking mechanism 141, described below, is provided at an end portion ofthe detection lever 75 opposite from the distal end portion 75 a as aworking end thereof.

The detection lever 75 configured in this manner is mounted so as to berotatable by a predetermined angle about a rotation support 74, and isdisposed so that the distal end portion 75 a projects in the directionclosing the reversing path 27 by the urging force of the urging member76.

The urging force of the urging member 76 is weak, so that the detectionlever 75 is rotated by a slight force such as a force of passage of thepaper P and the distal end portion 75 a of the detection lever 75 can beretracted from the reversing path 27.

The blocked-state locking mechanism 141 is provided at the working endof the detection lever 75, and includes the restricting member 143formed of a projecting portion having a wedge shape in side view and anengaging projection 145 having a trapezoidal shape in side view, beingprovided partly on a peripheral surface on the side of a free end of therocking motion of the cam lever 129 and coming into abutment with therestricting member 143, for example.

The cam lever 129 rotates when the discharge drive roller 15 is rotatedin the reverse direction CW and the paper P enters the reversing path 27in a state in which the cam lever 129 locates the intermediate gear 105at the first position 115. When the detection lever 75 detects thepassage of the leading end of the paper P, the restricting member 143comes into abutment with the engaging projection 145 to lock the powerblocked state by restricting the rocking movement of the cam lever 129.

In contrast, when the detection lever 75 detects the passage of thetrailing end of the paper P entered into the reversing path 27, thedetection lever 75 rotates in the direction in which the distal endportion 75 a closes the reversing path 27 by the urging force of theurging member 76, and hence the restricting member 143 moves away fromthe engaging projection 145, and locking of the power blocked state isreleased.

Therefore, the cam lever 129 is allowed to rock in the predetermineddirection by the rotation of the drive motor in the normal directionCCW, and the intermediate gear 105 is moved to the second position 117to transmit the rotation in the direction to cause the dischargingrollers 13 into the nipped state to the cam drive gear 57 (FIG. 16).

Subsequently, a working state of the paper transporting device 31Aaccording to the first embodiment configured as described above will bedescribed in parts (1) during the first surface transport, (2) during afirst half of the second surface transport, and (3) during a latter halfof the second surface transport.

(1) During the First Surface Transport (see FIG. 2, FIG. 3, FIG. 9, FIG.10, and FIG. 17).

The paper P set on the feeding tray 39 with the first surface 3 faced upis picked up by the pick roller 47 and, on the way, is separated by theseparating roller 49 and the separating pad 51 from the subsequent paperP, so that only the topmost paper P is delivered to the transport path19.

The paper P delivered to the transport path 19 is fed to the firsttransporting unit 21 with the first surface 3 faced up, is reversedupside down in the turning portion 23, and is fed to the transportingrollers 7 with the first surface 3 faced down.

The drive motor rotates in the normal direction CCW during the firstsurface transport and, in FIG. 10, the rotation in the direction shownby an arrow is transmitted to the gear train, and the discharge rollerdrive gear 89 rotates in the normal direction CCW, which is a directionto discharge the paper P to the outside.

The solar gear 97 of the planetary gear mechanism 95 rotates clockwisein FIG. 10 to engage the second planetary gear 103 with the intermediategear 105 to rotate the intermediate gear 105. At this time, since thetooth missing portion 111 for home position opposes the intermediategear 105, the power is not transmitted to the cam drive gear 57, and thedischarging rollers 13 maintains the nipped state shown in FIG. 17.

In addition, the rotation of the discharge roller drive gear 89 istransmitted to the cam lever drive gear train 137 via the secondtransmission gear 96, and the power transmitted to the cam lever drivegear train 137 is transmitted to the cam lever 129 via the frictionclutch 131, and the cam lever 129 rocks counterclockwise in FIG. 10 toposition the intermediate gear 105 to the second position 117.

The paper P fed to a nip point of the transporting rollers 7 istransferred toward the image processing executing unit 35 of the secondtransporting unit 25 with the first surface 3 faced down by the rotationof the transporting rollers 7 in the normal direction CCW transmittedvia the roller driving gear train for transport, not shown.

In the image processing executing unit 35, an image recorded on thefirst surface 3 of the paper P is scanned by the image scanning portion83 in sequence from the leading end to the trailing end of the paper Pin accordance with the transport of the paper P, and is saved as imagedata.

When the paper P reaches the nip point of the discharging rollers 13,the paper P is discharged outside of the transport path 19 by therotation of the discharging rollers 13 in the normal direction CCW andthe discharge is stopped in a state shown in FIG. 3.

(2) During the First Half of the Second Surface Transport (See FIG. 3 toFIG. 5, FIG. 11 to FIG. 14, FIG. 17, and FIG. 18).

When the paper P reaches the state shown in FIG. 3, the rotation of thedrive motor is switched to the reverse direction CW. Accordingly, thedischarging rollers 13 rotate in the reverse direction CW while keepingthe nipped state, and the paper P discharged to the outside of thetransport path 19 is guided to the reversing path 27. Then, as shown inFIG. 4, the leading end 69 of the paper P comes into abutment with thedistal end portion 75 a of the detection lever 75 projecting to thereversing path 27. When the passage of the leading end 69 of the paper Pis detected, the blocked-state locking mechanism 141 starts operation toachieve a state in which the counterclockwise movement of the cam lever129 can be locked.

The transmission of the power when the drive motor rotates in thereverse direction CW is as shown in FIG. 11, and the rotation in thedirection indicated by an arrow in FIG. 11 is transmitted to the geartrain. The rotation in the reverse direction CW which causes the paper Pto enter the reversing path 27 is transmitted to the discharge rollerdrive gear 89 as described above.

The solar gear 97 of the planetary gear mechanism 95 rotatescounterclockwise in FIG. 11 to engage the first planetary gear 101directly with the entirely toothed portion 107 of the cam drive gear 57to rotate the cam drive gear 57 counterclockwise in FIG. 11.

In addition, the rotation of the discharge roller drive gear 89 istransmitted to the cam lever drive gear train 137 via the secondtransmission gear 96. Then, the power transmitted to the cam lever drivegear train 137 is transmitted to the cam lever 129 via the frictionclutch 131, and the cam lever 129 rocks clockwise in FIG. 11 to positionthe intermediate gear 105 to the first position 115.

The paper P entered into the reversing path 27 with the second surface 5faced up is fed to a position upstream of the turning portion 23 of thetransport path 19, reversed upside down by the turning portion 23, andis fed to the transporting rollers 7 with the second surface 5 faceddown (FIG. 5).

Since the transporting rollers 7 are configured to rotate in the normaldirection CCW in the normal state even when the direction of rotation ofthe drive motor is switched by the roller driving gear train fortransport, not shown, the transporting rollers 7 pinch the fed paper Pand transports the same toward the image processing executing unit 35 onthe downstream thereof.

As shown in FIG. 18, the rotation of the drive motor is switchedtemporarily in the normal direction CCW at a position immediately afterthe leading end 69 of the paper P has passed through the transportingrollers 7. At this time, the roller driving gear train for transport,not shown, is configured so that the transporting rollers 7 rotatetemporarily in the normal direction CCW. By the temporary switching ofthe direction of rotation of the transporting rollers 7, skew(inclination) occurring on the paper P being transported is removed, sothat the paper P can be fed to the image processing executing unit 35 inthe normal position.

After the removal of the skew as described above, the dischargingrollers 13 start movement toward the released state as shown in FIG. 18by the rotation of the cam drive gear 57 which receives the power fromthe first planetary gear 101.

When the leading end 69 of the paper P reaches at a position shown inFIG. 5 (the state in which the leading end 69 of the paper P is nippedby the transporting rollers 7) and the discharging rollers 13 are in thereleased state, the rotation of the drive motor is switched from thereverse direction CW to the normal direction CCW, and the power istransmitted from the second planetary gear 103 to the cam drive gear 57via the intermediate gear 105.

When the cam drive gear 57 further rotates, the distal end portion 61 aof the cam 61 is brought into the released state shown in FIG. 14, inwhich the distal end portion 61 a moves the roller holder 18 to theuppermost position. When the discharge roller drive gear 89 is switchedfrom the reverse direction CW to the normal direction CCW in the stateshown in FIG. 11, a rotational force directed toward the position shownin FIG. 10 acts on the cam lever 129. However, since the cam lever 129is in the locked state by the detection lever 75 (FIG. 12), the camlever 129 is kept at the position shown in FIG. 12. Accordingly, theintermediate gear 105 is located at the first position 115 where theintermediate gear 105 opposes the tooth missing portion 113 for releaseposition, when the cam drive gear 57 rotates and opposes the toothmissing portion 113 for release position, the transmission of the powerto the cam drive gear 57 is blocked (the blocking-locked state in FIG.18).

In other words, in this state, since the tooth missing portion 113 forrelease position of the cam drive gear 57 is moved to a positionopposing the intermediate gear 105 locked at the first position 115, thepower is not transmitted to the cam drive gear 57, and hence thereleased state of the discharging rollers 13 is continued.

(3) During the Latter Half of the Second Surface Transport, See FIG. 3to FIG. 7, FIG. 9, FIG. 10, and FIG. 13 to FIG. 18.

The released state of the discharging rollers 13 is continuedcorresponding to the length of the paper P and, in the case of the longpaper P, the second surface transport of the paper P is performed in thestate of allowing the both ends of the paper P to pass with each otherat the nip of the discharging rollers 13 as shown in FIG. 6. The imagerecorded on the second surface 5 is scanned by the image scanningportion 83 in sequence, and the paper P having scanned the image thereonis discharged to the outside of the transport path 19 in sequence withthe first surface 3 faced up.

In addition, as shown in FIG. 7, when the trailing end 71 of the paper Ppasses through the position of abutment with the distal end portion 75 aof the detection lever 75, the detection lever 75 rotatescounterclockwise in FIG. 15 by the urging force of the urging member 76and unlocks the power blocked state with respect to the cam drive gear57 by the engagement between the restricting member 143 and the engagingprojection 145.

When the locked state of the blocked-state locking mechanism 141 isreleased, the cam lever 129 is allowed to rock counterclockwise in FIG.15 by the rotation of the drive motor in the normal direction CCW, sothat the power from the cam lever drive gear train 137 is transmitted tothe cam lever 129 by utilizing the engagement of the sector gear portion138 and the frictional force with respect to the friction clutch 131 asshown in FIG. 16.

The intermediate gear 105 moves to the second position 117 in the axialdirection G by the rocking movement of the cam lever 129, moves out fromthe tooth missing portion 113 for release position, and engages the camdrive gear 57. Therefore, the rotation of the second planetary gear 103is transmitted to the cam drive gear 57 via the intermediate gear 105.

The discharging rollers 13 are gradually translated toward the nippedstate in association with the rotation of the cam drive gear 57. Then,the discharging rollers 13 are brought into the nipped state and apply afeeding force to the paper P. From then on, upon receipt of atransporting force from the transporting rollers 7 and the dischargingrollers 13, the remaining second surface transport to the trailing end71 of the paper P and scanning of the image recorded on the secondsurface 5 are performed, and then the paper P is discharged to theoutside from the transport path 19 with the first surface 3 faced up.

The cam drive gear 57 is further rotated, and the rotation of the camdrive gear 57 is stopped at a position where the tooth missing portion111 for home position opposes the intermediate gear 105.

When discharge of the paper P with the second surface 5 faced up iswanted, it is achieved by performing again the second surface transportdescribed in (2) and (3) above in a state in which the image processingexecuting unit 35 is not activated. Second Embodiment, see FIG. 19 toFIG. 27

A paper transporting device 31B according to a second embodimentdescribed later can be mounted in the scanner 1. In the papertransporting device 31B according to the second embodiment, thestructures of the transport path 19, the reversing path 27, the imageprocessing executing unit 35, the feeding tray 39, the transportingrollers 7, the discharging rollers 13, the roller driving gear train fortransport, the discharge roller drive gear train 87, and the planetarygear mechanism 95 are the same as those of the paper transporting device31A according to the first embodiment. As regards the nip-releaseswitching mechanism 55, the configurations other than those of the camdrive gear 57 is the same as the paper transporting device 31A accordingto the first embodiment.

Therefore, in the following description, only configurations of a camdrive gear 57B, an intermediate gear 105B, a detection lever 75B, apower transmission switching mechanism 121B, and a blocked-state lockingmechanism 141B, which are different from those in the paper transportingdevice 31A in the first embodiment are intensively described.

In this embodiment, a gear having a structure in which a first cam drivegear 151 formed with teeth over the entire circumference and a secondcam drive gear 153 formed with the tooth missing portion 111 for homeposition partially on a peripheral surface thereof are integrallyconnected by a connecting shaft member 155 is used as the cam drive gear57B.

As shown in FIG. 28, the first planetary gear 101 engages the first camdrive gear 151 when the drive motor rotates in the reverse direction CW,so that the power is transmitted to the cam shaft 59 via the first camdrive gear 151.

As shown in FIG. 29, when the drive motor rotates in the normaldirection CCW, the rotation is transmitted to the second cam drive gear153 via the second planetary gear 103, the intermediate gear 105B, andthe power transmission switching mechanism 121B, the cam drive gear 57Brotates in the same direction as in the case where the drive motorrotates in the reverse direction CW.

The intermediate gear 105B is different from the one in the firstembodiment and has a fixed structure which is not allowed to move in theaxial direction G, and is provided at a position which does not allowengagement with the first cam drive gear 151.

The power transmission switching mechanism 121B includes a primary-sidegear train 159, a primary-side clutch disk 165, a secondary-side clutchdisk 173, an urging member 175, and a secondary-side gear train 177. Theprimary-side gear train 159 includes two gears, namely, a first gear159A and a second gear 159B which achieves transmission of the power byengaging the intermediate gear 105B. The primary-side clutch disk 165integrally includes a transmission gear portion 161 and a claw gear 163which engage the second gear 159B. The secondary-side clutch disk 173integrally includes an engaging claw 167 engaging the claw gear 163 andprojecting on the inner periphery side, a locking strip 169 projectingon the outer periphery side, which is a component of the blocked-statelocking mechanism 141B, described later, and a transmission gear portion171, the urging member 175 formed of a tension coil spring providedbetween the primary-side clutch disk 165 and the secondary-side clutchdisk 173 in an expanded state and configured to urge the engaging claw167 to always engage the claw gear 163. The secondary-side gear train177 includes a third gear 177A which engages the second cam drive gear153, a fourth gear 177B which engages the third gear 177A, and a fifthgear 177C which engages the fourth gear 177B and the transmission gearportion 171.

A clutch mechanism 179 includes the primary-side clutch disk 165, thesecondary-side clutch disk 173, and the urging member 175 providedtherebetween in the expanded state, and the clutch mechanism 179 isconfigured as so-called a one-way clutch (one-time clutch), whichtransmits the power from the primary-side clutch disk 165 to thesecondary-side clutch disk 173, but does not transmit the power from thesecondary-side clutch disk 173 to the primary-side clutch disk 165.

As shown in FIG. 19, FIG. 21, FIG. 23, and FIG. 25, the detection lever75B is made up of a parallel link mechanism including a first rockinglink 183 which makes a rocking movement about a rocking support 181provided on the supporting frame 32, a second rocking link 187 whichmakes a rocking movement about a rocking support 185 provided on thesupporting frame 32, and a rocking bar 193 connected to a free end ofthe rocking motion of the first rocking link 183 at a rotation support189, connected to a free end of the rocking motion of the second rockinglink 187 at a rotation support 191 and reciprocating toward the clutchmechanism 179.

The second rocking link 187 is integrally provided with a detectionstrip 195 extending toward the path of the paper P in the reversing path27 so as to be slightly inclined in the direction along the direction ofentry of the paper P.

The rocking bar 193 is a component of the blocked-state lockingmechanism 141B, described below, and is configured to be capable ofreciprocating between a hooking position 197 entered into a rotationaltrajectory of the locking strip 169 and a retracted position 199retracted from the rotational trajectory.

An urging force of an urging device, not shown is applied to the rockingbar 193. In a state in which the paper P does not exist in the reversingpath 27, the detection strip 195 extending from the second rocking link187 projects into the reversing path 27, and closes the path of thepaper P.

The blocked-state locking mechanism 141B basically includes the lockingstrip 169 provided for the clutch mechanism 179 and the rocking bar 193provided for the detection lever 75B.

The locking strip 169 is integrally supported by an annular resilientsupporting ring 201 having a predetermined width together with theengaging claw 167 which engages the claw gear 163. In contrast, therocking bar 193 is supported by the first rocking link 183 and thesecond rocking link 187 described above so as to allow switching betweenthe hooking position 197 at which the rocking bar 193 abuts against thelocking strip 169 and the retracted position 199 at which it does notabut against the locking strip 169.

When the locking strip 169 is not in abutment with the rocking bar 193,the resilient supporting ring 201 maintains the power transmitting statein which the axial center thereof is aligned with the axial center ofclutch mechanism 179 and the engaging claw 167 is engaged with the clawgear 163. In contrast, when the locking strip 169 is in abutment withthe rocking bar 193, the resilient supporting ring 201 is resilientlydeformed, and is moved to a position deviated from the axial center ofthe clutch mechanism 179 to release the engagement between the engagingclaw 167 and the claw gear 163, so that a retained state in which thetransmission of the power is blocked is assumed.

Subsequently, a working state of the paper transporting device 31Baccording to the second embodiment configured as described above duringthe second surface transport will be described in parts (1) whenswitching to the second surface transport, (2) when the leading end ofthe paper is detected, (3) when the power transmission blocking state islocked, and (4) when the transmission of the power is restarted.

(1) When Switching to the Second Surface Transport, See FIG. 17, FIG.19, FIG. 20, and FIG. 28

When the first surface transport performed by the rotation of the drivemotor in the normal direction CCW is ended, the trailing end of thepaper P (the leading end 69 of the paper P at the time of the secondsurface transport) in the direction of transport is brought into a statenipped by the discharging rollers 13 which is shown in FIG. 17 and FIG.19.

Then, the direction of rotation of the drive motor is switched from thenormal direction CCW to the reverse direction CW, and the second surfacetransport of the paper P is started.

The transmission of the power when the drive motor is switched to thereverse direction CW is as indicated by arrows in FIG. 20 and FIG. 28,and the first planetary gear 101 engages the first cam drive gear 151 ofthe cam drive gear 57B by the rotation of the solar gear 97 in thedirection indicated by the arrows, so that the rotation of the firstplanetary gear 101 is directly transmitted to the cam drive gear 57B.

Since the third gear 177A of the secondary-side gear train 177 describedabove engages the second cam drive gear 153, the power is transmittedthrough the third gear 177A, the fourth gear 177B, and the fifth gear177C, and the clockwise rotation in FIG. 20 is transmitted to thesecondary-side clutch disk 173 via the transmission gear portion 171.

Since it is configured that the power is not transmitted from thesecondary-side clutch disk 173 to the primary-side clutch disk 165, theprimary-side clutch disk 165 stays stopped.

(2) When the Leading End of the Paper is Detected (See FIG. 21, FIG. 22,and FIG. 28).

The paper P enters the reversing path 27 with the second surface 5 facedup by the rotation of the discharging rollers 13 in the reversedirection CW. When the leading end 69 of the paper P comes into abutmentwith the detection strip 195 of the detection lever 75B as shown in FIG.21, the first rocking link 183 and the second rocking link 187 rocksimultaneously as shown in the drawing to move the rocking bar 193located at the retracted position 199 to the hooking position 197.

The power transmitting state at this time is the same as that whenswitching the second surface transport in (1) shown above.

(3) When Blocking of the Power Transmission is Locked, See FIG. 14, FIG.23, FIG. 24, and FIG. 29

The paper P entered into the reversing path 27 is supplied to theupstream portion of the turning portion 23 in the transport path 19, isreversed upside down in the turning portion 23, and is supplied to thetransporting rollers 7 rotating in the normal direction CCW with thesecond surface 5 faced down.

Then, in the same manner as the case in the embodiment 1, theskew-removing operation is performed for the paper P, and the paper P isfed toward the image processing executing unit 35.

At a timing when the leading end 69 of the paper P reaches a positionnear a midpoint between the transporting rollers 7 and the imageprocessing executing unit 35, the direction of rotation of the drivemotor is switched from the reverse direction CW to the normal directionCCW, and the rotation of the cam drive gear 57 is advanced to move thedischarging rollers 13 gradually to the released state.

The transmission of the power when the drive motor is switched to thenormal direction CCW is as indicated by arrows in FIG. 24 and FIG. 29,and the second planetary gear 103 engages the intermediate gear 105 bythe rotation of the solar gear 97 in the direction indicated by anarrow. Then, the power is transmitted further from the first gear 159Ato the second gear 159B, which constitutes the primary-side gear train159, and the counterclockwise rotation in FIG. 24 is transmitted to theprimary-side clutch disk 165 via the transmission gear portion 161.

The rotation of the primary-side clutch disk 165 is transmitted to thesecondary-side clutch disk 173 via the claw gear 163 and the engagingclaw 167 which are engaged with each other, and the power is transmittedfurther from the transmission gear portion 171 of the secondary-sideclutch disk 173 to the fifth gear 177C, the fourth gear 177B, and thethird gear 177A which constitute the secondary-side gear train 177 insequence, so that the power is finally transmitted to the second camdrive gear 153 of the cam drive gear 57B.

The direction of rotation of the cam drive gear 57B in this case is thesame direction as the case where the drive motor shown in FIG. 22 andFIG. 28 is rotated in the reverse direction CW.

When the leading end 69 of the paper P passes through the imageprocessing executing unit 35, where the scanning of the image on thesecond surface 5 is started, and reaches a position before thedischarging rollers 13 shown in FIG. 23, the discharging rollers 13assume the released state shown in FIG. 14. Since the locking strip 169of the blocked-state locking mechanism 141 comes into abutment with therocking bar 193 located at the hooking position 197, the engagementbetween the claw gear 163 and the engaging claw 167 is released as shownin FIGS. 23 and 24, so that the transmission of the power to the camdrive gear 57B is blocked.

Therefore, the second surface transport of the paper P and the imagescanning of the second surface 5 are performed with the dischargingrollers 13 still in the released state.

(4) When the Transmission of the Power is Restarted, See FIGS. 25, 26and 29

When the second surface transport of the paper P is advanced and thetrailing end 71 of the paper P reaches a position shown in FIG. 25passing through the detection strip 195 of the detection lever 75B, therocking bar 193 is moved from the hooking position 197 to the retractedposition 199 by the urging force of the urging device, not shown.

When the rocking bar 193 moves to the retracted position 199, the stateof abutment between the locking strip 169 and the rocking bar 193 isreleased. Therefore, the engaging claw 167 engages the claw gear 163again, and the rotation of the primary-side clutch disk 165 istransmitted to the secondary-side clutch disk 173.

Then, the rotation of the secondary-side clutch disk 173 is transmittedto the cam drive gear 57B via the secondary-side gear train 177, thedischarging rollers 13 are translated to the nipped state by therotation of the cam drive gear 57B, and the rotation of the cam drivegear 57B is brought into a stopped state at a position where the toothmissing portion 111 for home position opposes the third gear 177A.

In the state shown in FIG. 25, the paper P is transported upon receiptof the transporting force in the normal direction CCW from the two setsof rollers, namely, the transporting rollers 7 and the dischargingrollers 13 and, after the trailing end 71 of the paper P has passedthrough the nip point of the transporting rollers 7, the discharge tothe outside of the transport path 19 is performed only by the nippingand transporting force of the discharging rollers 13.

In this case, the paper P discharged from the discharging rollers 13 isdischarged with the first surface 3 faced up. However, if the dischargeof the paper P with the second surface 5 faced up, the second surfacetransport in (1) to (4) shown above is performed again in a state inwhich the image processing executing unit 35 is not activated as in thecase of the first embodiment.

In the case of the paper transporting device 31B according to the secondembodiment having a configuration as described above, a phase shiftoccurs between the clutch mechanism 179 and the cam drive gear 57B atthe time point when the first surface transport is ended depending onthe length of the paper P.

In this case, the phase shift with respect to the cam drive gear 57B canbe prevented by performing the detection of the home position of theclutch mechanism 179 using a sensor or the like and correcting the phaseshift after having ended the first surface transport of the paper P, orby providing a separate mechanism which blocks the rotation of thesecondary-side gear train 177 or the secondary-side clutch disk 173which are idled by the transmission of the rotation of the cam drivegear 57B when the drive motor rotates in the reverse direction CW, forexample, a mechanism which causes some of gears which constitute thesecondary-side gear train 177 to slide in the axial direction G to avoidthe engagement, a one-way clutch mechanism or a planetary gearmechanism.

Alternatively, even when the phases of the clutch mechanism 179 and thecam drive gear 57B cannot be aligned after having ended the firstsurface transport, by setting the number of steps of the drive motorduring the first surface transport and the reduction gear ratio of therespective gear trains with respect to a paper P having a specificlength which causes the phase of the clutch mechanism 179 to be alwaysthe same, the continuous double-sided transport for the first surface 3and the second surface 5, which is unaffected by the phase shift, can beachieved for the paper P having the above-described in question and apaper P having a length which is integral multiple of theabove-described length.

A countermeasure for the phase shift between the clutch mechanism 179and the cam drive gear 57B is specifically effective for making thetiming of starting the image scanning by the image processing executingunit 35 constant.

Other Embodiments

The transported material transporting device 31 and the image processingapparatus 1 according to the invention basically have the configurationas described above. However, partial modifications or omissions of theconfiguration within a range not departing from the scope of theinvention in the present application are possible as a matter of course.

For example, the paper transporting device 31 of the invention may beapplied not only to the image scanning device such as a scanner whichperforms the image scanning continuously for the first surface 3 and thesecond surface 5 of the paper P, but may be applied to the imageprocessing apparatus 1 which performs various image processing actionscontinuously on both the first surface 3 and the second surface 5 of thepaper P such as image printing apparatuses such as an ink jet printerwhich performs printing continuously on both the first surface 3 and thesecond surface 5 of the paper P.

For example, when the paper transporting device 31 in the invention isapplied to the ink jet printer, a mode of layout in which a printhead isdisposed above the image processing executing unit 35, and a papersupporting portion is disposed below the image processing executing unit35 may be employed, for example.

As another mode of the image processing executing unit 35, an imageinspecting device configured to check the presence or absence ortrue-false of a content printed on the paper P or a colorimeterconfigured to obtain color information from a colorimetric patternprinted on the paper P may be employed. Alternatively, the imageprocessing executing unit 35 may be omitted to singly use the papertransporting device 31.

Alternatively, instead of the power transmission switching mechanism 121which is configured to move the intermediate gear 105 in the axialdirection G using the cam lever 129 employed in the first embodiment,the power transmission switching mechanism 121 can be configured usingother mechanisms such as a rack and pinion mechanism or a linkmechanism.

In addition, the configuration of the blocked-state locking mechanism141 is not limited to the one in the first embodiment in which therestricting member 143 provided directly for the detection lever 75 andthe engaging projection 145 provided on the peripheral surface of thecam lever 129, but various configurations having the similar powertransmission blocking state locking action such as a configuration inwhich a separate restricting member which moves in conjunction with themovement of the detection lever 75 or a configuration in which part ofthe restricting member is engaged with an engaging slit or an engaginghole formed on the cam lever 129 may be employed.

It is also possible to add a separate feeding roller or a guide rollerto the transport path 19 or the reversing path 27 so as to support thetransport of the paper P having smaller dimensions, and the material tobe transported P as the object to be transported is not limited to thepaper, but may be synthetic resin films such as the polyester film orthe like. Images appearing on the first surface 3 and the second surface5 of the material to be transported P may be characters or graphicsprinted directly by the image printing apparatus, images such asphotographs, or figures or patterns appearing on a front surface bymaking with patterns such as Japanese Paper.

What is claimed is:
 1. A transported material transporting devicecomprising: a transporting roller configured to transport a material tobe transported on a transport path by rotating in a direction of normalrotation; a discharging roller configured to discharge the material tobe transported on the transport path by rotating in the direction ofnormal rotation, deliver the material to be transported to thetransporting roller via a reversing path by rotating in a direction ofreverse rotation, and be capable of assuming a nipped state and areleased state; a drive motor that serves as a driving source of thetransporting roller and the discharging roller; a nip-release switchingmechanism configured to switch the state of the discharging rollerbetween the nipped state and the released state by the rotationalposition of a cam drive gear; a planetary gear mechanism including afirst planetary gear configured to transmit a power to the cam drivegear when the drive motor rotates in one direction and a secondplanetary gear configured to transmit the rotation in the same directionas the first planetary gear to the cam drive gear via an intermediategear when the drive motor rotates in the other direction; a powertransmission switching mechanism configured to switch the transmissionof the power between the intermediate gear and the cam drive gearbetween a transmitted state and a blocked state; a detection leverprovided in the reversing path and configured to detect the presence orabsence of the material to be transported which enters the reversingpath; and a blocked-state locking mechanism configured to lock theblocked state of the power transmission switching mechanism when thedischarging roller is in the released state, wherein the locked state ofthe blocked-state locking mechanism is released and the powertransmission switching mechanism is switched from the blocked state tothe transmitted state upon detection of the position of the trailing endof the material to be transported entering the reversing path by thedetection lever.
 2. The transported material transporting deviceaccording to claim 1, wherein the cam drive gear includes on aperipheral surface thereof an entirely toothed portion formed with teethover the entire circumference and a partially toothed portion providedpartially with a tooth missing portion for home position and a toothmissing portion for release position, both of which are parts having notooth provided partly on the peripheral surface, the first planetarygear engages the entirely toothed portion and the intermediate gearengages the partially toothed portion, and the intermediate gear isconfigured to be capable of being moved by the power transmissionswitching mechanism between a first position formed with both the toothmissing portion for home position and the tooth missing portion forrelease position and a second position formed only with the toothmissing portion for home position in an axial direction.
 3. Thetransported material transporting device according to claim 2, whereinthe power transmission switching mechanism includes: a cam leverprovided with a solid cam coming into abutment with an end surface ofthe intermediate gear and having a cam height in the axial direction,and configured to rock about a rocker shaft within a range of therocking angle; a frictional clutch configured to come into press contactwith the cam lever and transmit a power; and a cam lever drive geartrain configured to transmit the rotation of the drive motor to thefrictional clutch.
 4. The transported material transporting deviceaccording to claim 3, wherein the cam lever includes a sector gearportion configured to transmit the power by engaging the intermediategear when moving the intermediate gear from the first position to thesecond position.
 5. An image processing apparatus comprising: an imageprocessing executing unit provided in a transport path at a positionbetween a transporting roller and a discharging roller and configured toexecute image processing actions continuously on an opposed surface of amaterial to be transported which is transported by the transportingroller; and a transported material transporting device configured toswitch the direction of transport of the material to be transported tocause the material to be transported to enter a reversing path andreverse the same so that a first surface and a second surface oppositetherefrom are opposed to the image processing executing unit afterhaving executed the image processing on a first surface of the materialto be transported, wherein the transported material transporting deviceis the transported material transporting device according to claim
 4. 6.The transported material transporting device according to claim 3,wherein the blocked-state locking mechanism includes a restrictingmember provided at a working end of the detection lever and an engagingprojection provided on part of a peripheral surface of the cam lever andcoming into abutment with the restricting member, the restricting membercomes into abutment with the engaging projection to restrict the rockingmovement of the cam lever after the material to be transported entersthe reversing path and the detection lever detects the passage of aleading end of the material to be transported until the passage of atrailing end of the material to be transported is detected in a state inwhich the cam lever locates the intermediate gear at the first position.7. An image processing apparatus comprising: an image processingexecuting unit provided in a transport path at a position between atransporting roller and a discharging roller and configured to executeimage processing actions continuously on an opposed surface of amaterial to be transported which is transported by the transportingroller; and a transported material transporting device configured toswitch the direction of transport of the material to be transported tocause the material to be transported to enter a reversing path andreverse the same so that a first surface and a second surface oppositetherefrom are opposed to the image processing executing unit afterhaving executed the image processing on a first surface of the materialto be transported, wherein the transported material transporting deviceis the transported material transporting device according to claim
 6. 8.An image processing apparatus comprising: an image processing executingunit provided in a transport path at a position between a transportingroller and a discharging roller and configured to execute imageprocessing actions continuously on an opposed surface of a material tobe transported which is transported by the transporting roller; and atransported material transporting device configured to switch thedirection of transport of the material to be transported to cause thematerial to be transported to enter a reversing path and reverse thesame so that a first surface and a second surface opposite therefrom areopposed to the image processing executing unit after having executed theimage processing on a first surface of the material to be transported,wherein the transported material transporting device is the transportedmaterial transporting device according to claim
 3. 9. An imageprocessing apparatus comprising: an image processing executing unitprovided in a transport path at a position between a transporting rollerand a discharging roller and configured to execute image processingactions continuously on an opposed surface of a material to betransported which is transported by the transporting roller; and atransported material transporting device configured to switch thedirection of transport of the material to be transported to cause thematerial to be transported to enter a reversing path and reverse thesame so that a first surface and a second surface opposite therefrom areopposed to the image processing executing unit after having executed theimage processing on a first surface of the material to be transported,wherein the transported material transporting device is the transportedmaterial transporting device according to claim
 2. 10. An imageprocessing apparatus comprising: an image processing executing unitprovided in a transport path at a position between a transporting rollerand a discharging roller and configured to execute image processingactions continuously on an opposed surface of a material to betransported which is transported by the transporting roller; and atransported material transporting device configured to switch thedirection of transport of the material to be transported to cause thematerial to be transported to enter a reversing path and reverse thesame so that a first surface and a second surface opposite therefrom areopposed to the image processing executing unit after having executed theimage processing on a first surface of the material to be transported,wherein the transported material transporting device is the transportedmaterial transporting device according to claim 1.